Pablo Guides

## Section 1: Introduction to Hurl

### Understanding Hurl

Hurl is a powerful command-line tool designed primarily for sending HTTP requests and analyzing responses. It is particularly useful in pentesting scenarios where security professionals need to explore web applications, test for vulnerabilities, and simulate attacks. With Hurl, you can craft complex HTTP requests with ease, enabling you to test various aspects of web services, such as authentication, session management, and API security.

This section will guide you through the installation and configuration of Hurl on Kali Linux, its usage with detailed use cases, and provide you with code examples to facilitate the learning process.

### Installation and Configuration on Kali Linux

#### Prerequisites

Before we begin, ensure that you have the following:

– A running instance of Kali Linux (make sure it’s updated).
– Basic knowledge of the Linux command line.
– An internet connection to download dependencies.

#### Steps to Install Hurl

1. **Update Your System**

Start by updating your package list and upgrading installed packages. Open the terminal and run:

   sudo apt update && sudo apt upgrade -y

 

2. **Install Dependencies**

Hurl requires certain dependencies to function correctly. Install them using:

   sudo apt install curl jq git -y

 

3. **Download Hurl**

You can download Hurl from its GitHub repository. Use the following command:

   git clone https://github.com/Orange-OpenSource/hurl.git

 

4. **Navigate to the Hurl Directory**

Change your working directory to the newly downloaded Hurl folder:

   cd hurl

 

5. **Compile Hurl**

To compile Hurl, run the following command:

   go build

 

This will create an executable named `hurl` in the current directory.

6. **Move Hurl to Your PATH**

To use Hurl from anywhere in your terminal, move the executable to a directory in your PATH:

   sudo mv hurl /usr/local/bin/

 

7. **Verify Installation**

To ensure Hurl is installed correctly, check its version:

   hurl –version

 

If you see the version number, the installation is successful!

### Basic Configuration

Hurl can be configured using a configuration file, allowing you to set default settings that apply to all your requests.

1. **Create a Configuration Directory**

   mkdir -p ~/.hurl

 

2. **Create a Configuration File**

You can create a configuration file named `hurl.yaml` to store your settings:

   nano ~/.hurl/hurl.yaml

 

Example configuration:

[/dm_code_snippet]yaml
default:
headers:
User-Agent: "Hurl/1.0"
Accept: "application/json"
timeout: 10
[/dm_code_snippet]

Save and exit the editor.

### Step-by-Step Usage and Real-World Use Cases

Now that Hurl is installed and configured, let’s explore how to use it effectively. This section presents various scenarios that pentesters may encounter.

#### Basic Request

To make a simple GET request to a website, you can use:

"`bash
hurl GET https://jsonplaceholder.typicode.com/posts
"`

#### Use Case 1: Testing API Endpoints

Imagine you’re testing an API for vulnerabilities. You may want to check the response for different inputs.

**Example: Testing a login endpoint**

"`bash
hurl POST https://example.com/api/login
–data '{"username": "testuser", "password": "testpass"}'
–header "Content-Type: application/json"
"`

This will send a POST request to the login endpoint with the specified credentials.

#### Use Case 2: Checking for CSRF Tokens

When interacting with forms, ensure that CSRF (Cross-Site Request Forgery) tokens are checked.

"`bash
hurl GET https://example.com/form
"`

Check if the CSRF token is present in the response body.

#### Use Case 3: Session Management Testing

You can test for session fixation or expiration by using cookies:

"`bash
hurl GET https://example.com/dashboard
–cookie "sessionid=abcd1234efgh5678"
"`

#### Use Case 4: Exploiting Vulnerabilities

If you discover a vulnerability like SQL Injection, you can test it using crafted requests:

"`bash
hurl GET 'https://example.com/api/items?id=1 OR 1=1'
"`

#### Advanced Features of Hurl

– **Chaining Requests**: Hurl allows you to chain multiple requests together, making it easier to automate complex workflows.

"`bash
hurl GET https://example.com/api/login
–data '{"username": "testuser", "password": "testpass"}'
&&
hurl GET https://example.com/api/user
–cookie "sessionid=$(hurl -o sessionid GET https://example.com/api/login –data '{"username": "testuser", "password": "testpass"}' | jq '.sessionid')"
"`

– **Using Variables**: You can define variables in Hurl to use across your requests, making your scripts cleaner and more manageable.

"`yaml
vars:
baseUrl: "https://example.com"

requests:
– method: GET
url: "{baseUrl}/api/resource"
"`

### Detailed Technical Explanations

#### How Hurl Handles Requests

Hurl sends HTTP requests using native HTTP methods like GET, POST, PUT, and DELETE. It handles both JSON and form URL-encoded data, making it versatile for various web application interactions.

When you specify headers, Hurl automatically includes them in the request, allowing you to simulate different user agents, content-types, and authentication methods.

#### Parsing Responses

Hurl can parse JSON responses using tools like `jq`:

"`bash
hurl GET https://jsonplaceholder.typicode.com/posts | jq '.[] | {userId, title}'
"`

This extracts and formats specific fields from the response, simplifying data analysis.

### External Reference Links

1. [Hurl Official Documentation](https://hurl.dev)
2. [Kali Linux Official Documentation](https://www.kali.org/docs/)
3. [OWASP Penetration Testing Guide](https://owasp.org/www-project-web-security-testing-guide/latest/)
4. [Understanding CSRF Attacks](https://owasp.org/www-community/attacks/csrf)
5. [SQL Injection Overview](https://owasp.org/www-community/attacks/SQL_Injection)

### Conclusion

Hurl is an essential tool for any pentester and cybersecurity professional. It empowers you to interact with web applications through HTTP requests efficiently, making it easy to identify vulnerabilities and test the security of web services.

In the following sections, we will delve deeper into specific features of Hurl, including automation, integration with CI/CD pipelines, and advanced scripting techniques to maximize your pentesting effectiveness.

—

Made by pablo rotem / פבלו רותם